Grassland Species Research Articles

Dominant species of mid-elevation grasslands of the uKhahlamba-Drakensberg Park are predicted to be largely immune to climate change

Dominant species of mid-elevation grasslands of the uKhahlamba-Drakensberg Park are predicted to be largely immune to climate change

The Historic Square Foot Dataset – Outstanding small‐scale richness in Swiss grasslands around the year 1900

AbstractGrasslands host a significant share of Europe's species diversity but are among the most threatened vegetation types of the continent. Resurvey studies can help to understand patterns and drivers of changes in grassland diversity and species composition. However, most resurveys are based on local or regional data, and hardly reach back more than eight decades. Here, we publish and describe the Historic Square Foot Dataset, comprising 580 0.09‐m2 and 43 1‐m2 vegetation plots carefully sampled between 1884 and 1931, covering a wide range of grassland types across Switzerland. We provide the plots as an open‐access data set with coordinates, relocation accuracy and fractional aboveground biomass per vascular plant species. We assigned EUNIS habitat types to most plots. Mean vascular plant species richness in 0.09 m2 was 19.7, with a maximum of 47. This is considerably more than the present‐day world record of 43 species for this plot size. Historically, species richness did not vary with elevation, differing from the unimodal relationship found today. The data set provides unique insight into how grasslands in Central Europe looked more than 100 years ago, thus offering manifold options for studies on the development of grassland biodiversity and productivity.

Reconstructed Global Invasion and Spatio-Temporal Distribution Pattern Dynamics of Sorghum halepense under Climate and Land-Use Change.

Sorghum halepense competes with crops and grass species in cropland, grassland, and urban environments, increasing invasion risk. However, the invasive historical dynamics and distribution patterns of S. halepense associated with current and future climate change and land-use change (LUC) remain unknown. We first analyzed the invasive historical dynamics of S. halepense to explore its invasion status and expansion trends. We then used a species distribution model to examine how future climate change and LUC will facilitate the invasion of S. halepense. We reconstructed the countries that have historically been invaded by S. halepense based on databases with detailed records of countries and occurrences. We ran biomod2 based on climate data and land-use data at 5' resolution, assessing the significance of environmental variables and LUC. Sorghum halepense was widely distributed worldwide through grain trade and forage introduction, except in Africa. Europe and North America provided most potential global suitable habitats (PGSHs) for S. halepense in cropland, grassland, and urban environments, representing 48.69%, 20.79%, and 84.82%, respectively. The future PGSHs of S. halepense increased continuously in the Northern Hemisphere, transferring to higher latitudes. Environmental variables were more significant than LUC in predicting the PGSHs of S. halepense. Future PGSHs of S. halepense are expected to increase, exacerbating the invasion risk through agricultural LUC. These results provide a basis for the early warning and prevention of S. halepense worldwide.

Unraveling the Relationship between Percentage Cover and Biomass of Various Herbaceous Species in the Dry Tropical Grassland

The estimation of biomass and cover is an ideal variable for determining ecosystem productivity, vegetation abundance, and community structure of any ecosystem. Biomass estimation by harvest method causes a huge loss of biomass and biodiversity. Non-destructive methods are helpful for repeated and regular sampling of the same plot to measure any change in biomass at the fixed time interval. There are already several regression equations established between biomass and cover in various ecosystems for finding above-ground biomass but there was an urgent need for such studies in dry tropical grasslands. The experiment was performed in the entire campus of Banaras Hindu University, Varanasi. 115 Quadrats were sampled in the entire university campus during year 2019-2020. For each quadrat, species-wise individual numbers were recorded and above-ground biomass was estimated by harvest method. Herbage cover was recorded for each species and measured by gridding each 1×1 m2 quadrat into 100 cells of 10 × 10 cm cells, each representing 1% cover. We found 59 herbaceous species of 28 different families. The family Asteraceae was the most common while only single species represented the other seventeen families. Most of the species like Dichanthium annulatum, Sida acuta, Ageratum conyzoides, Malvastrum coromandelianum, Rungia pectinate, and Vernonia cinerea showed linear regression equation, Parthenium hysterophorus, Alternenthera sessilis, Boerhavia diffusa showed quadratic polynomial trendlines. Species like Zephyranthes citrina and Ruellia tuberosa showed a power regression equation. Only Andrographis paniculata, and Chenopodium album showed an exponential regression equation. A power regression equation was found between pooled biomass and cover. Using the regression equations biomass of the listed 59 species could be calculated easily without disturbing the vegetation of the study area which will eventually help in the conservation of nature.

Linking plant traits to rhizosphere priming effects across six grassland species with and without nitrogen fertilization

The rhizosphere priming effect (RPE), i.e., the acceleration of soil organic matter decomposition (SOM) by plant roots, plays a key role in the soil carbon (C) cycle and its feedback to climate change. However, how plant traits regulate the RPE has rarely been investigated. Here we selected six grassland species with and without nitrogen (N) fertilization to examine the relationships between the RPE and plant traits, and also the interactive effect of plant traits and N fertilization on the RPE. All six species showed positive RPEs, ranging from 83% to 297% above the unplanted control. Among plant traits, specific rhizosphere respiration was the best predictor for the interspecific variation in the RPE, with the higher RPE related to higher specific rhizosphere respiration. The RPE was also positively linked to root N concentration across species. In contrast, leaf traits and root morphological or architectural traits could not explain the interspecific variation in the RPE. Nitrogen fertilization differentially affected the RPEs of six species through its interaction with plant traits and the effect on soil processes. Nitrogen fertilization increased leaf N concentration and specific rhizosphere respiration, causing higher photosynthesis and possibly root exudation. On the other hand, N fertilization increased mineral N, and decreased soil pH, β-glucosidase and β-cellobiohydrolase, causing lower microbial activities. The effect of N fertilization on the RPE was thus attributed to the balance between the changes in microbial activities and in plant traits. Overall, our results demonstrate that the variation of RPE across six species could be mainly explained by plant biomass and traits. It is promising that plant traits have important indicative functions in predicting the SOM decomposition through plant-soil interactions.

Soil phosphorus availability alters the correlations between root phosphorus-uptake rates and net photosynthesis of dominant C3 and C4 species in a typical temperate grassland of Northern China.

Phosphorus (P) fertilization can alleviate a soil P deficiency in grassland ecosystems. Understanding plant functional traits that enhance P uptake can improve grassland management. We measured impacts of P addition on soil chemical and microbial properties, net photosynthetic rate (Pn ) and nonstructural carbohydrate concentrations ([NSC]), and root P-uptake rate (PUR), morphology, anatomy, and exudation of two dominant grass species: Leymus chinensis (C3 ) and Cleistogenes squarrosa (C4 ). For L. chinensis, PUR and Pn showed a nonlinear correlation. Growing more adventitious roots compensated for the decrease in P transport per unit root length, so that it maintained a high PUR. For C. squarrosa, PUR and Pn presented a linear correlation. Increased Pn was associated with modifications in root morphology, which further enhanced its PUR and a greater surplus of photosynthate and significantly stimulated root exudation (proxied by leaf [Mn]), which had a greater impact on rhizosheath micro-environment and microbial PLFAs. Our results present correlations between the PUR and the Pn of L. chinensis and C. squarrosa and reveal that NSC appeared to drive the modifications of root morphology and exudation; they provide more objective basis for more efficient P-input in grasslands to address the urgent problem of P deficiency.

An Analysis of Functional Groups and Potential Values of Herbaceous Species of Grasslands in West Timor, Indonesia

An Analysis of Functional Groups and Potential Values of Herbaceous Species of Grasslands in West Timor, Indonesia

Effects of extracts from various parts of invasive Solidago species on the germination and growth of native grassland plant species.

Allelopathy is an important factor influencing whether an invasive plant species can become successfully established in a new range through disrupting the germination and growth of native plant species. Goldenrods (Solidago species) are one of the most widespread invasive taxa in Central Europe of North American origin. Owing to their high environmental impact and wide distribution range, invasive Solidago species should be controlled in Europe, and the areas invaded by them should be restored. Numerous studies have reported the allelopathic effects of Solidago gigantea and Solidago canadensis, but the results are inconsistent regarding differences in the allelopathic effects of particular plant parts and in the sensitivity to Solidago allelopathic effects among native species as well as between the two invasive species themselves. In this study, we aimed to analyse the effect of water extracts from S. canadensis and S. gigantea parts (roots, rhizomes, stems, leaves, and inflorescences) on the germination and initial growth of seedlings of 13 grassland species that typically grow in Central Europe. The tested grassland species differed in susceptibility to Solidago allelopathy, with the most resistant species being Schedonorus pratensis, Lolium perenne, Trifolium pratense, Daucus carota and Leucanthemum vulgare. The inhibitory effect of 10% water extracts from leaves and flowers were stronger than those from rhizomes, roots, and stems without leaves, regardless of the Solidago species. Our study results imply that reducing the allelopathic effect of Solidago during habitat restoration requires removal of the aboveground parts, including fallen leaves. The allelopathic effects of roots and rhizomes seem to be of secondary importance.

Multi-Temporal Hyperspectral Classification of Grassland Using Transformer Network.

In recent years, grassland monitoring has shifted from traditional field surveys to remote-sensing-based methods, but the desired level of accuracy has not yet been obtained. Multi-temporal hyperspectral data contain valuable information about species and growth season differences, making it a promising tool for grassland classification. Transformer networks can directly extract long-sequence features, which is superior to other commonly used analysis methods. This study aims to explore the transformer network's potential in the field of multi-temporal hyperspectral data by fine-tuning it and introducing it into high-powered grassland detection tasks. Subsequently, the multi-temporal hyperspectral classification of grassland samples using the transformer network (MHCgT) is proposed. To begin, a total of 16,800 multi-temporal hyperspectral data were collected from grassland samples at different growth stages over several years using a hyperspectral imager in the wavelength range of 400-1000 nm. Second, the MHCgT network was established, with a hierarchical architecture, which generates a multi-resolution representation that is beneficial for grass hyperspectral time series' classification. The MHCgT employs a multi-head self-attention mechanism to extract features, avoiding information loss. Finally, an ablation study of MHCgT and comparative experiments with state-of-the-art methods were conducted. The results showed that the proposed framework achieved a high accuracy rate of 98.51% in identifying grassland multi-temporal hyperspectral which outperformed CNN, LSTM-RNN, SVM, RF, and DT by 6.42-26.23%. Moreover, the average classification accuracy of each species was above 95%, and the August mature period was easier to identify than the June growth stage. Overall, the proposed MHCgT framework shows great potential for precisely identifying multi-temporal hyperspectral species and has significant applications in sustainable grassland management and species diversity assessment.

Plant drought adaptation strategies regulate alpine grassland water yield in the Qinghai Lake Basin, northeastern Qinghai-Tibet Plateau

Study regionThe Qinghai Lake Basin, northeast Qinghai-Tibetan Plateau. Study focusVegetation dynamic induced change on catchment water yield (including surface runoff and groundwater runoff) is one of the research hotspots in the field of hydrology and ecology. However, few studies have explored the underlying biological mechanism by which plant regulate water yield. In this study, we examined the impact of different plant drought adaptation strategies on watershed water yield in the Qinghai Lake Basin, using both the ecohydrological model, water balance method and surface runoff experiments. New hydrological insightswe defined two type of plant drought adaptation strategies: drought-avoiding strategy can maximize the soil moisture and therefore minimize vegetation water stress, while drought-tolerating strategy tends to increase productivity by tolerating a certain degree of water stress. The result shows that plants employing drought-avoiding strategy have significantly higher water yield and water yield coefficient (the ratio of water yield to precipitation) than plants adopting drought-tolerating strategy, regardless of meadow or steppe species. Meanwhile, for all grassland species in the study region, plants with drought-avoiding strategy have less vegetation cover and net primary productivity than plants with drought-tolerating strategy, which reflect the trade-off between avoiding water stress and achieving competitive advantages. Our findings offer insights into the biological mechanism by which vegetation regulates water yield, and provide vital guidance for watershed management.

Spatial Distribution of Leymus chinensis Is Not Determined by Its Ecological Stoichiometry

Leymus chinensis is a widely distributed species of Eurasian grasslands that is well adapted to a range of environmental conditions. In this study, we measured soil and plant chemical elements to examine the basis of the ecological adaptations of L. chinensis to temperate steppe. We sampled leaves of L. chinensis and soil layers at different latitudes in temperate steppe for three consecutive years from 2012 to 2014. One-way analysis of variance and linear regression were used to analyze the variation in foliar nitrogen (N) and phosphorus (P) contents and the N:P ratio in L. chinensis. The correlations between the foliar N:P ratio and the variation in soil total nitrogen (TN) and total P contents with latitudinal gradient were measured to explore the homeostasis stoichiometry of foliar N and P in L. chinensis. With increasing latitude, both the foliar N and P contents of L. chinensis showed parabolic trends with significant negative correlations. The population of L. chinensis was limited by N, and the soil TN content showed a significant increasing trend with the increase in the foliar N:P ratio. The variation in the foliar N:P ratio of L. chinensis was determined through the variation in the soil N content. In different latitude intervals, the foliar N, P, and N:P ratio of L. chinensis showed absolute stability and strong internal stability, and the values of HN:P were high and similar in different latitudes. In conclusion, the population of L. chinensis in the temperate steppe is highly adaptable; and, thus, can maintain a dominant position in the variable environment and has a wide distribution range.

Spatio-temporal modelling of the effect of environmental and land-use factors on species-rich calcareous grasslands

The abundance of sensitive plant species in calcareous grasslands is threatened by agricultural intensification with nutrient addition and increased livestock densities as well as by land abandonment. The Hill-Shannon diversity is decreasing, and the species composition of Danish calcareous grassland is generally unstable and is expected to experience further change in the coming years. In order to quantify the effects of selected environmental and land-use factors on the observed variation and changes in the vegetation of calcareous grasslands, large-scale spatial and temporal pin-point plant cover monitoring data are fitted in a structural equation model. The analyzed vegetation data come from 100 Danish sites monitored over an eight-year period. The important sources of measurement and sampling uncertainties have been included using a hierarchical model structure. Furthermore, the measurement and sampling uncertainties are separated from the process uncertainty, which is important when generating ecological predictions that may feed into local conservation management decisions. There were significant negative effects of grazing and nitrogen deposition on the change in cover of sensitive plant species. Whereas the negative effect of nitrogen deposition on the cover of sensitive species was expected, it was surprising that the model results suggest that sensitive species may be subjected to overgrazing by the grazing regimes that are currently applied at protected Danish calcareous grasslands. The standardized regression coefficients suggest that the effects of both grazing and nitrogen deposition are relatively benign compared to the effects of soil type, soil pH and precipitation. The relatively large effect of precipitation is interesting, since it is predicted that the amount of precipitation and its distribution over the seasons will change due to climate change, and the results suggest that climate change may lead to important species compositional changes in calcareous grasslands. The fitted model may be used to quantify the uncertainties when generating ecological forecasting and local adaptive management plans. More specifically, this study suggests that it is relevant to rethink the currently used criteria for vegetation height when assessing the conservation status of calcareous grasslands.

Negative effects of EPDM microplastic and cork granules on plant growth are mitigated by earthworms and likely caused by their structural properties

Soil microplastic pollution can have negative effects on organisms, including plants, but the underlying mechanisms are not fully understood. We tested whether structural or chemical properties of a microplastic cause its effects on plant above- and belowground growth and whether these effects can be influenced by earthworms. We conducted a factorial experiment in a greenhouse with seven common Central European grassland species. Microplastic granules of the synthetic rubber ethylene propylene diene monomer (EPDM),11EPDM: ethylene propylene diene monomer. a frequently used infill material of artificial turfs, and cork granules with a comparable size and shape to the EPDM granules were used to test for structural effects of granules in general. To test for chemical effects, EPDM-infused fertilizer was used, which should have contained any leached water-soluble chemical components of EPDM. Two Lumbricus terrestris individuals were added to half of the pots, to test whether these earthworms modify effects of EPDM on plant growth. EPDM granules had a clear negative effect on plant growth, but since cork granules had a negative effect of similar magnitude, with an average decrease in biomass of 37 % in presence of granules, this is likely due to the structural properties of granules (i.e., size and shape). For some belowground plant traits, EPDM had a stronger effect than cork, which shows that there must be other factors playing into the effects of EPDM on plant growth. The EPDM-infused fertilizer did not have any significant effect on plant growth by itself, but it had in interaction with other treatments. Earthworms had an overall positive effect on plant growth and mitigated most of the negative effects of EPDM. Our study shows that EPDM microplastic can have negative effects on plant growth, and that these might be more related to its structural than to its chemical properties.

The role of drought, disturbance, and seed dispersal in dominance shifts in a temperate grassland

AbstractAimsMore intense and frequent droughts predicted for the future will heavily affect grasslands worldwide and, along with various other disturbances, possibly trigger major vegetation shifts. Therefore, documenting these changes and understanding the mechanisms behind them is essential. Our study aimed to investigate how dominant species in a semiarid grassland respond to a combination of small‐scale experimental disturbances and naturally occurring droughts and uncover the underlying mechanisms.LocationCentral Hungary.MethodsWe conducted a small‐scale disturbance experiment in a semiarid temperate grassland and followed recovery for 18 years, including severe drought events. In 1999, we established 16 sites, eight dominated by Festuca vaginata and another eight by Stipa borysthenica, the two dominant species of sand grasslands in the region. At each site, three permanent plots were marked that received either a cutting or digging treatment or remained as controls. We monitored the cover and density changes of Festuca and Stipa annually.ResultsIn the early years following the disturbance, Festuca recovered at a similar rate under both disturbance treatments, while Stipa recovered faster in cut than in dug plots. When natural drought events caused major diebacks of both species, Stipa recovered very quickly and regained dominance in initially Stipa‐dominated plots, and it also took over in initially Festuca‐dominated control and cut plots. However, digging at Festuca‐dominated sites delayed drought‐induced Stipa colonisation and thus favoured Festuca recovery. We found that the poor performance of Stipa in dug plots was related to sharply reduced seedling establishment, which resulted from the low number of seeds captured by the bare soil surface after digging.ConclusionsOur results demonstrate that recurring drought events may induce dominance shifts in temperate grasslands, but small‐scale disturbances can modulate vegetation responses. Our findings emphasise the importance of post‐disturbance regeneration patterns in drought‐induced vegetation shifts and show that seed dispersal strategy may have a major effect on vegetation dynamics.

High-mountain phylogeography in the Balkan Peninsula: isolation pattern in a species of alpine siliceous grasslands and its possible background

Although the Balkan Peninsula belongs to the most mountainous regions of Europe, phylogeographic structure of its alpine flora remains insufficiently understood, especially for species distributed both in the western and eastern parts of the Peninsula. We analyzed Campanula orbelica, a Balkan endemic typical of high-mountain siliceous grasslands, based on the population genetic structure, climatic niche modeling at the species- and intraspecific level, and niche hindcasting back to the Last Glacial Maximum (LGM; 20 kya). Our data reveal a clear phylogeographic pattern with three geographically coherent genetic groups: (i) the most divergent and spatially restricted lineage of the Pirin mountains (east), (ii) neighboring Rila mountains and other eastern Balkan massifs (Rhodopes, Stara Planina, Vitoša), and (iii) the most geographically disjunct mountains of the Scardo-Pindhic range (Šar Planina and Korab) in the west. This pattern indicates multiple refugia and isolated evolutionary centers within the Balkan Peninsula mountains, with the eastern part of the range as likely ancestral area, and an early dispersion into the western region, which formed the main geographical disjunction. The genetic divergence was only partly correlated with geographical isolation, clear dispersal barriers, or climatic niche shifts, suggesting contrasting isolation/dispersal dynamics in various parts of the range. Climatic niche overlap was low among eastern vs. western groups, which correlates with the longest spatial distance and significant genetic divergence, while niche characteristic of the Pirin lineage was a subset of the adjacent Rila lineage niche. High genetic divergence of the Pirin populations was also not correlated with persistent gaps in potential distributions but hypothetically may have been triggered by diversified (limestone/silicate) bedrock conditions. Our results highlight the need for high-mountain phylogeographic surveys in the eastern part of the Balkan Peninsula, to assess the biogeographical relevance of isolation patterns and definition of evolutionarily important units in the high-mountain flora.

Large‐scale restoration of species‐rich dry grasslands on arable land: Environmental filtering drives successful species establishment over a period of 10 years

Abstract Sowing of regionally specific seed mixtures on former arable land is increasingly used to restore species‐rich grasslands but it often faces important obstacles in environmental conditions and colonisation from preserved surrounding grasslands. Long‐term landscape scale studies, which explore the processes governing plant establishment from seed mixtures and later colonisation from the surrounding landscape are scarce. We studied the species and functional trait composition of 32 grasslands restored 1–11 years before the first sampling by sowing regional seed mixtures in the White Carpathian Mts (SE Czech Republic). We compared them with 23 well‐preserved permanent grasslands in their surroundings. In each grassland, we estimated plant species cover in three plots of 25 m2, in restored grasslands in 2009, 2014 and 2019, in permanent grasslands in 2009. The species composition of the restored grasslands converged towards the permanent grasslands due to expansion of dry grassland species and retreat of mesic grassland and weed species. The majority (60%–71%) of the vegetation cover of restored grasslands was formed by sown species, while the species number was mainly determined by colonising unsown species (61%–63%). The species number of restored grasslands remained lower than that in permanent grasslands. Functional trait composition (community weighted mean) of the sown seed mixtures, permanent grasslands and restored grasslands overlapped in all three samplings. With increasing grassland age, species with resource‐retaining traits of low specific leaf area and high leaf dry matter content, lower stature, higher seed mass and lower capacity for clonal reproduction expanded. Functional trait diversity of the plots was mostly lower than expected by null model randomisations of community, which indicates strong environmental filtering. Comparison of newly colonising species and extinct species indicated that mainly species with traits similar to the rest of the community are able to colonise the grasslands successfully. Synthesis and applications: Sowing of regionally specific seed mixtures was successful and demonstrated to be a fast way of grassland restoration, particularly in terms of functional trait composition. The resulting species diversity depended on the colonisation processes, which are controlled by the functional composition of the local communities.

Drought Eliminates the Difference in Root Trait Plasticity and Mycorrhizal Responsiveness of Two Semiarid Grassland Species with Contrasting Root System.

Root traits and arbuscular mycorrhizal (AM) fungi are important in determining the access of plants to soil resources. However, whether plants with different root systems (i.e., taproot vs. fibrous-root) exhibit different root trait plasticity and mycorrhizal responsiveness under drought remains largely unexplored. Tap-rooted Lespedeza davurica and fibrous-rooted Stipa bungeana were grown in monocultures in sterilized and live soils, followed by a drought treatment. Biomass, root traits, root colonization by AM fungi, and nutrient availability were evaluated. Drought decreased biomass and root diameter but increased the root:shoot ratio (RSR), specific root length (SRL), soil NO3--N, and available P for the two species. Under control and drought conditions, soil sterilization significantly increased the RSR, SRL, and soil NO3--N for L. davurica, but this only occurs under drought condition for S. bungeana. Soil sterilization significantly reduced AM fungal root colonization of both species, but drought significantly increased it in live soil. In water-abundant conditions, tap-rooted L. davurica may depend more on AM fungi than fibrous-rooted S. bungeana; however, under drought conditions, AM fungi are of equal importance in favoring both plant species to forage soil resources. These findings provide new insights for understanding the resource utilization strategies under climate change.

Plant-soil feedback effects on conspecific and heterospecific successors of annual and perennial Central European grassland plants are correlated.

Plant-soil feedbacks (PSFs), soil-mediated plant effects on conspecific or heterospecific successors, are a major driver of vegetation development. It has been proposed that specialist plant antagonists drive differences in PSF responses between conspecific and heterospecific plants, whereas contributions of generalist plant antagonists to PSFs remain understudied. Here we examined PSFs among nine annual and nine perennial grassland species to test whether poorly defended annuals accumulate generalist-dominated plant antagonist communities, causing equally negative PSFs on conspecific and heterospecific annuals, whereas well-defended perennial species accumulate specialist-dominated antagonist communities, predominantly causing negative conspecific PSFs. Annuals exhibited more negative PSFs than perennials, corresponding to differences in root-tissue investments, but this was independent of conditioning plant group. Overall, conspecific and heterospecific PSFs did not differ. Instead, conspecific and heterospecific PSF responses in individual species' soils were correlated. Soil fungal communities were generalist dominated but could not robustly explain PSF variation. Our study nevertheless suggests an important role for host generalists as drivers of PSFs.

Precipitation and local adaptation drive spatiotemporal variations of aboveground biomass and species richness in Tibetan alpine grasslands.

The Tibetan Plateau contains the highest and largest alpine pasture in the world, which is adapted to the cold and arid climate. It is challenging to understand how the vast alpine grasslands respond to climate change. We aim to test the hypothesis that there is local adaptation in elevational populations of major plant species in Tibetan alpine grasslands, and that the spatiotemporal variations of aboveground biomass (AGB) and species richness (S) can be mainly explained by climate change only when the effect of local adaptation is removed. A 7-year reciprocal transplant experiment was conducted among the distribution center (4950m), upper (5200m) and lower (4650m) limits of alpine Kobresia meadow in central Tibetan Plateau. We observed interannual variations in S and AGB of 5 functional groups and 4 major species, and meteorological factors in each of the three elevations during 2012-2018. Relationships between interannual changes of AGB and climatic factors varied greatly with elevational populations within a species. Elevation of population origin generally had a greater or an equal contribution to interannual variation in AGB of the 4 major species, compared to temperature and precipitation effects. While the effect of local adaptation was removed by calculating differences in AGB and S between elevations of migration and origin, relative changes in AGB and S were mainly explained by precipitation change rather than by temperature change. Our data support the hypothesis, and further provide evidence that the monsoon-adapted alpine grasslands are more sensitive to precipitation change than to warming.

The contribution of seedbank to the green roof plant community dynamics analogous to semi-natural grasslands

Extensive green roofs have been shown to support native biodiversity and plant communities that are analogous to natural or semi-natural habitats such as grasslands. However, little is known about the role of soil seedbanks in the dynamic of extensive green roof plant communities. The purpose of this study was to analyze the seedbank that developed after 4 years of an extensive green roof analog to dry grassland plant community, seeded with 29 species. We aimed to understand the contribution of seedbank to the resilience of vegetation to harsh conditions of the roof and to colonization by surrounding spontaneous species. We monitored the plant species cover in 36 plots during 4 years in June (between 2018 and 2021), and sampled the seedbank in February 2021. Our results showed that the soil seedbank was dominated by transient spontaneous ruderals species, while the standing vegetation was still dominated by seeded grassland species. We found that seeded grassland species had poor seedbank stock, similar to their natural environments. The similarity index between the standing vegetation and the seedbank increased over time, and we measured a significant correlation between dominant species cover and their seedbank density. Spontaneous species cover was not correlated to the proportion of soil not colonized by seeded species cover, indicating that gaps in vegetation did not influence the development of spontaneous species. Our findings highlight the importance of seedbank in the dynamic of green roof vegetation and demonstrate that analogous habitat species exhibit similar behavior as in their natural environments.